1. Technical Field
The present invention relates to a liquid ejecting apparatus such as an ink jet printer.
2. Related Art
A liquid ejecting apparatus is an apparatus including a liquid ejecting head and each of various liquids is ejected from this liquid ejecting head. As a typical example of this liquid ejecting apparatus, an image recording apparatus can be given, such as an ink jet printer (simply called a printer hereafter) including an ink jet type recording head (called simply a recording head), being a liquid ejecting head, constituted to perform recording by ejecting liquid ink as ink droplets, from this recording head to recording paper, etc, being an ejection target, and causing these ink droplets to impact on the ejection target to form dots. In recent years, this kind of liquid ejecting apparatus has been applied not only to image recording apparatuses but also to various kinds of manufacturing apparatuses such as display manufacturing apparatuses.
The aforementioned liquid ejecting head may be one equipped with, for example, piezoelectric elements as a pressure generating unit (driving source) for ejecting liquid. This piezoelectric element is constituted of a multilayer structure of a piezoelectric material made of PZT (lead zirconate titanate) and an electrode material, and elastic deformation or bending deformation of this piezoelectric element is made to occur by applying a voltage between a driving electrode and a common electrode. This piezoelectric element is joined to a diaphragm for partitioning a part of a pressure generation chamber that communicates with a nozzle opening, and by applying a drive signal in such a manner as drive deforming of the piezoelectric element, the diaphragm can be deformed. By deformation of this diaphragm, the volume of the pressure generation chamber is changed to allow pressure fluctuation to occur in the ink in the pressure generation chamber, and by controlling this pressure fluctuation, the liquid can be discharged (ejected) from the opening of the nozzle.
Then, in the liquid ejecting head using the aforementioned piezoelectric element as a driving source, an amount of the liquid ejected according to a voltage value of the drive signal is increased or decreased. Therefore, JP-A-11-58729 proposes a technique of setting an optimal voltage value as the drive signal for driving the piezoelectric element.
However, when the aforementioned printer is used over a long period of time, the piezoelectric element is gradually deteriorated, and its characteristics are changed (an amount of displacement is lowered). In this case, there is a possibility that even if the piezoelectric element is driven by the drive signal of the drive voltage set at the time of manufacture, the amount of the ejected ink or a flight speed of the ink does not coincide with a design value.